So, Now What's Your Sign?

An astrological controversy erupted online Thursday after a newspaper article erroneously suggested that the dates that determine the Zodiac signs had shifted by about a month, throwing millions of believers into self-doubt and panic.

The tilt of the Earth's axis has gradually shifted since the ancient times when the Babylonians determined the dates of the Zodiac. The calendrical rejiggering also supposedly re-introduced a sign discarded by the Babylonians: Ophiuchus, alternatively called the much-cooler sounding Serpentarius.

Under this calculus your correspondent, an erstwhile Aquarius, is now a Capricorn.

But astrologers and astronomers -- two groups that don't always see eye-to-eye -- agree that this is old news. About 3,000 years old. Western astrologers included the wobble of the Earth's axis in their calculations centuries ago. The Zodiac we are all familiar with is still perfectly valid (as valid, anyway, as the Zodiac ever was).

"Astronomers have known about this since 130 BC. Hipparchus was able to determine that this would happen," says Parke Kunkle, a board member of the Minnesota Planetarium Society. "It astounds me that this has taken off the way it has in the last day or two."

The popular astrologer Susan Miller called the news "ridiculous." In an interview with ABC News, she said, "We've known about this for ages. The constellations don't suggest what's coming up, it's the planets! The constellations are a measuring device."

"In ancient days there were, like, 50 constellations. Then they finally got together and agreed on 18. Then they narrowed it down," says Miller. "I'm getting so many tweets. Trying to explain something technical in 140 characters is hard!"

Out of Alignment

What has changed, subtly and very gradually, is the tilt of the earth's axis as it revolves around the sun. If you watch a spinning toy top, explains Kunkle, you will see its axis wobble. That's called precession. The Earth's axis does the same thing. It's currently facing Polaris, often called the North Star, but 3,000 years ago it was pointing at an obscure star called Thuban.

"Three thousand years ago the sun was 'in' whatever it was in," says Kunkle, who is also a professor at Minneapolis Community and Technical College. "Now it's about a whole constellation off from that."

In an August 2009 Pew poll, 25 percent of Americans said they believed in astrology; 71 percent said they did not. Kunkle falls into the latter category ("I'm a scientist," he says drily.)

But, he says, "You could predict when to harvest, when to plant, by the stars. So there is some predictive nature there. Then they took it too far, using it to determine when to go to war and people's personalities."

Jane Zimmerman can take some solace in that. A stay-at-home mom in San Francisco, Zimmerman was just this week told by an older, wise-looking lady that she and her husband Jason had compatible signs. "I took heart," she jokes. "I was glad."

But Zimmerman, 37, was born on Dec. 2, meaning that her "new" sign would be Ophicius while her husband remained a Pisces.

"When it suits me, the Zodiac is great. If it's going to tell me that I'm not a great match to Jason, then it's a load of crap," she says. "Unless we don't get along any more. If there start to be cracks in our relationship, I guess I'll know what to blame."